<!DOCTYPE html>
<html lang="en">
	<head>
		<meta charset="utf-8">
		<title>D3: Adding and removing values from a chart (dynamic labels included)</title>
		<script type="text/javascript" src="../d3.js"></script>
		<style type="text/css">
			/* No style rules here yet */
		</style>
	</head>
	<body>
	
		<p id="add">Add a new data value</p>
		<p id="remove">Remove a data value</p>
			
		<script type="text/javascript">

			//Width and height
			var w = 600;
			var h = 250;
			
			var dataset = [ { key: 0, value: 5 },		//dataset is now an array of objects.
							{ key: 1, value: 10 },		//Each object has a 'key' and a 'value'.
							{ key: 2, value: 13 },
							{ key: 3, value: 19 },
							{ key: 4, value: 21 },
							{ key: 5, value: 25 },
							{ key: 6, value: 22 },
							{ key: 7, value: 18 },
							{ key: 8, value: 15 },
							{ key: 9, value: 13 },
							{ key: 10, value: 11 },
							{ key: 11, value: 12 },
							{ key: 12, value: 15 },
							{ key: 13, value: 20 },
							{ key: 14, value: 18 },
							{ key: 15, value: 17 },
							{ key: 16, value: 16 },
							{ key: 17, value: 18 },
							{ key: 18, value: 23 },
							{ key: 19, value: 25 } ];
			
			var xScale = d3.scaleBand()
							.domain(d3.range(dataset.length))
							.rangeRound([0, w])
							.paddingInner(0.05);
			
			var yScale = d3.scaleLinear()
							.domain([0, d3.max(dataset, function(d) { return d.value; })])
							.range([0, h]);
			
			//Define key function, to be used when binding data
			var key = function(d) {
				return d.key;
			};
			
			//Create SVG element
			var svg = d3.select("body")
						.append("svg")
						.attr("width", w)
						.attr("height", h);

			//Create bars
			svg.selectAll("rect")
			   .data(dataset, key)
			   .enter()
			   .append("rect")
			   .attr("x", function(d, i) {
			   		return xScale(i);
			   })
			   .attr("y", function(d) {
			   		return h - yScale(d.value);
			   })
			   .attr("width", xScale.bandwidth())
			   .attr("height", function(d) {
			   		return yScale(d.value);
			   })
			   .attr("fill", function(d) {
					return "rgb(0, 0, " + (d.value * 10) + ")";
			   });

			//Create labels
			svg.selectAll("text")
			   .data(dataset, key)
			   .enter()
			   .append("text")
			   .text(function(d) {
			   		return d.value;
			   })
			   .attr("text-anchor", "middle")
			   .attr("x", function(d, i) {
			   		return xScale(i) + xScale.bandwidth() / 2;
			   })
			   .attr("y", function(d) {
			   		return h - yScale(d.value) + 14;
			   })
			   .attr("font-family", "sans-serif")
			   .attr("font-size", "11px")
			   .attr("fill", "white");




			//On click, update with new data			
			d3.selectAll("p")
				.on("click", function() {

					//See which p was clicked
					var paragraphID = d3.select(this).attr("id");
					
					//Decide what to do next
					if (paragraphID == "add") {
						//Add a data value
						var minValue = 2;
						var maxValue = 25 - minValue;
						var newNumber = Math.floor(Math.random() * maxValue) + minValue;
						var lastKeyValue = dataset[dataset.length - 1].key;
						dataset.push({
							key: lastKeyValue + 1,
							value: newNumber
						});
					} else {
						//Remove a value
						dataset.shift();	//Remove one value from dataset
					}
					
					//Update scale domains
					xScale.domain(d3.range(dataset.length));
					yScale.domain([0, d3.max(dataset, function(d) { return d.value; })]);

					//Select…
					var bars = svg.selectAll("rect")
						.data(dataset, key);
					
					//Enter…
					bars.enter()
						.append("rect")
						.attr("x", w)
						.attr("y", function(d) {
							return h - yScale(d.value);
						})
						.attr("width", xScale.bandwidth())
						.attr("height", function(d) {
							return yScale(d.value);
						})
						.attr("fill", function(d) {
							return "rgb(0, 0, " + (d.value * 10) + ")";
						})
						.merge(bars)	//Update…
						.transition()
						.duration(500)
						.attr("x", function(d, i) {
							return xScale(i);
						})
						.attr("y", function(d) {
							return h - yScale(d.value);
						})
						.attr("width", xScale.bandwidth())
						.attr("height", function(d) {
							return yScale(d.value);
						});

					//Exit…
					bars.exit()
						.transition()
						.duration(500)
						.attr("x", -xScale.bandwidth())
						.remove();



					//Update all labels
	
					//Select…
					var labels = svg.selectAll("text")
						.data(dataset, key);

  					//Exit…
  					labels.exit()
  						.transition()
  						.duration(500)
  						.attr("x", -xScale.bandwidth())
  						.remove();
					
					//Enter…
					labels.enter()
						.append("text")
						.text(function(d) {
							return d.value;
						})
						.attr("text-anchor", "middle")
						.attr("x", w)
						.attr("y", function(d) {
							return h - yScale(d.value) + 14;
						})						
					   .attr("font-family", "sans-serif")
					   .attr("font-size", "11px")
					   .attr("fill", "white")
					   .merge(labels)	//Update…
					   .transition()
					   .duration(500)
					   .attr("x", function(d, i) {
							return xScale(i) + xScale.bandwidth() / 2;
					   });

				});

			
		</script>
	</body>
</html>